Questions have come up about the meaning of “substantial and insubstantial” or “empty and full” in taiji theory. I’ve tried below to gather some thoughts and findings on some of the historical meanings of the terms that I hope will be interesting and helpful to folks in their own investigations and practice. The Chinese terms in question are “xu” and “shi.” These words have ranges of meaning that depend upon the context in which they are being used. Xu can mean "empty," "tenuous," "intangible," "insubstantial," "false," etc. Shi can mean “solid,” "full," "substantial," "real," “coming to fruition,” etc. Although I’ve used the English words “substantial and insubstantial” in the past to translate “xu and shi,” I’ve come to feel that “empty and full” are better renderings, and sometimes the gerund forms “emptying and filling” better still, because they better capture conceptually what in taiji is essentially processional rather than static.

More pertinant to taiji theory than the individual terms, however, are their combined use as a correlative pair: xu/shi. Significantly, perhaps the earliest occurance of xu/shi in this correlative pairing is in the Sunzi (The Art of Warfare, c. 400 B.C.E.). In the fifth chapter of that book, “Stategic Advantage” (Shi), the correlative pairing xu/shi is found in the following sentence: “If wherever the army attacks it is like a whetstone thrown against an egg, it is due to the vacuous and substantial [xu shi].” (Ralph Sawyer, trans., in The Seven Military Classics of Ancient China, p. 164) In Roger Ames’ excellent translation of Sunzi, he translates xu shi in this sentence as “weak points” and “strong points.” (Ames, Sun-tzu: The Art of Warfare, pp. 118-118) Although these meanings can apply, I find them limiting, and prefer Sawyer’s wording in this instance. Non-deployment of strength, after all, is not synonomous with weakness, and I don’t think Sunzi would have thought it so either. The importance of this point should not be lost on taijiquan practitioners.

The following chapter (six) of the Sunzi is in fact titled “Empty and Full” (Xu Shi). Here we find insights such as the following: “To attack with the confidence of taking one’s objective is because one attacks what the enemy does not defend. To defend with the confidence of keeping one’s charge secure is because one defends where the enemy will not attack.” (Ames, p. 123) The closing lines of this chapter, I think, have great bearing on the meaning of the correlative pairing xu/shi in taijiquan theory:

“Now the army’s disposition of force [xing] is like water. Water’s configuration [xing] avoids heights and races downward. The army’s disposition of force [xing] avoids the substantial [shi] and strikes the vacuous [xu]. Water configures [xing] its flow in accord with the terrain; the army controls its victory in accord with the enemy. Thus the army does not maintain any constant strategic configuration of power [shi]; water has no constant shape [xing]. One who is able to change and transform in accord with the enemy and wrest victory is termed spiritual! Thus [none of] the five phases constantly dominates; the four seasons do not have constant positions; the sun shines for longer and shorter periods; and the moon wanes and waxes.”—Sawyer, p. 168

So the summary lines of Sunzi’s chapter on Empty and Full emphasize this waxing and waning quality, the futility of fixed configurations, and the efficacy of fluid adaptation to changing circumstances. All of these qualities, I think, apply to empty and full in taiji theory.

The “waxing and waning” sense of xu/shi, probably appropriated from military theory, is also found in traditional Chinese medical theory. There shi refers to “energy abundance” or what Manfred Porkert terms “repletio,” and xu refers to “energy exhaustion” or “inanitas.” (Porkert’s Chinese Medicine, p. 71, cited in John Minford’s newly published Sunzi translation, The Art of War: The essential translation of the classic book of life, Viking, 2002, p. 177).

I believe that in taijiquan xu/shi seems to apply both in a strategic sense of interacting with a partner or adversary (responding and according to empty and full), and in an individual sense of monitoring and managing the ebb and flow of jin in one’s own movements. So both the military and medical models may have influenced the development of taiji theory. But there is an additional way that xu/shi comes into play: one of psychology. Here is where the entailments of “false” and “real” for xu and shi come into play. In the famous sixteenth century Chinese novel, San guo yan yi (Romance of the Three Kingdoms), there is a good deal of discussion of the tactical use of xu and shi. One general would try to anticipate the moves of another, and to entice his adversary with a show of emptiness, only to trap him with ambushes. One of the characters, Zhuge Liang, explicitly talks of using dissimulation (man), and of anticipating precisely what his adversary was anticipating HE was anticipating. He said to Guan Yu, “Have you not heard of the method of warfare of ‘[attacking] the empty with the empty and the solid with the solid [xu xu shi shi]’?” (quoted in Lisa Raphals, Knowing Words: Wisdom and Cunning in the Classial Traditions of China and Greece, p. 142) Eventually, the phrase “xu xu shi shi” became a set phrase for “feints and ambushes.” This same phrase appears in the taiji text thought to have been transmitted by Yang Banhou, the “Xu Shi Jue” (translated by Douglas Wile in T’ai-chi Touchstones, p. 76, as “The Secret of Full and Empty.” I’ve tried my hand at translating it here:

~~~Xu Shi JueUsing empty-empty full-full, the spirit gathers within.Using empty-full full-empty, hands trade merits.If in training quan you’re not versed in the principles of empty and full,It will be a waste of gongfu with no end result.Abiding in the empty, issuing the full; the knack is in the palm.If the center remains full, with no release, refinement will be elusive.Knowing that empty and full themselves contain empty and full,In applying empty-empty full-full, your attacks will not be in vain.—transmitted by Yang Banhou~~~

It’s a difficult text, but my sense of it is that the strategic, the internal energy, and the psychological applications of “empty and full” are all being addressed.

I also took a look in my Jingxuan Taijiquan Cidian (Dictionary of Essential Taijiquan Terms), and found an entry for the phrase, “xu shi fen ming” that seems to bear on recent discussions we’ve had. Here’s my rough translation of the entry:

~~~Empty and Full are Clearly Differentiated (xu shi fen ming):

A taijiquan training essential. Sometimes expressed “empty and full are clearly distinguished” (xu shi fen qing), or “distinguish empty and full” (fen xu shi). The problem of empty and full exists within every movement of taijiquan. That an empty part (chu4: place, point) contains fullness implies the impending transition to “full.” The full part must not be fixed (si3: rigid, lifeless), but still contains the pivotal condition of transformation. “Empty and Full are Clearly Differentiated” does not mean a cut and dried “separated” (fen kai).—Jingxuan Taijiquan Cidian, pp. 225-226~~~

The last sentence addresses the concept that differentiating empty and full is a matter of understanding correlative relationship, where, as Wang Zongyue’s “Taijiquan Treatise” states: “Yang does not leave yin; yin does not leave yang. The mutual cooperation of yin and yang is precisely what makes up the understanding of energy.” The Chinese word “fen” can mean “to separate, to cut apart,” but it also can mean to differentiate or distinguish. The above entry makes it explicit that the notion expressed in the “Taijiquan Classic” as “Empty and full must be clearly distinguished” does not mean to separate empty and full. The very next line in the classic is in my opinion one of the most profound: “Each point has its point of empty/full. Everywhere there is always this one empty/full.”

Here’s my translation of the Jingxuan Taijiquan Cidian entry for that phrase:~~~Each point has its point of empty/full. Everywhere there is always this one empty/full.

A famous taijiquan saying, coming from Wu Yuxiang’s “Taijiquan Classic.” Each point in taijiquan contains a contradictory pair of empty and full. When practicing quan, the hands and legs have empty and full; the skillfull deployment of opening and closing have empty and full; in fighting techniques, the opponent and myself entail empty and full; when issuing energy (fajin), the reserving and releasing entail empty and full. Hence some martial artists emphasize that taijiquan is in fact “empty/full boxing” (xu shi quan). Yet the many faceted transformations of empty and full converge under the greater principle [i.e., taiji] of empty/full, what is called “always this one empty/full.” This principle encompasses “within empty there is full, within full there is empty,” “empty and full mutually arise,” “empty and full mutually reflect,” “empty and full rely on one another,” “empty and full distinguish one another,” and so forth.—Jingxuan Taijiquan Cidian~~~

I’ll just observe that the wording “contradictory pair” is what I would call an amusing artifact of modern Chinese sociopolitical discourse. The word for contradiction, “maodun,” is quite old, from a story in the Han Feizi about a seller of spears and shields. But the word became an obligatory expression in Maoist China having Hegelian and Marxist overtones having to do with antagonistic dialectical relationships. In my opinion, the taiji relationship of xu/shi is correlative, but not essentially antagonistic.

In Li Yiyu’s “Five Key Words,” he stated: “Empty does not mean completely devoid of strength (li), and full does not mean to completely stand firm (zhan sha).” This understanding is echoed in Yang Chengfu’s discussion of empty and full in the legs in his “Discussion of Taijiquan Practice,” where he said, “What is here called empty is not void, for its power is not yet disconnected, but reserved and retained in the intention of the changes of expansion and contraction. What is called full is simply that it is sound and real—without excessive use of energy, which would mean use of fierce strength.”

All of the above indicates to me that the taiji theory of empty and full has clearly identifiable antecedents in early military concepts, traditional medicine and philosophy, and that it has strategic, internal energy, and psychological applications.

I look forward to comments, criticism, and reflections of personal experience.

That's what I have been saying (in my simple way)---just kidding---but not entirely. It took me quite some time to come to grips with this subject in the past. I always felt what was going on in my body but had no words that I was comfortable with---until I came up with my "If you can't respond..." It is about change/response....stepping, turn of the waist, issuing power, as I absoarb energy,.... I would add "livliness" that Zhu Tian Cai mentioned in the quote that I posted. I think that word is very appropriate for many aspects of this subject. I agree with just about everything you in your post above. I will have a question or two after doing some thinking and research. The "empty/empty,full/full" attacking---hmmmmm, have not thought exactly in those terms before---any elaboration? Very nice and thorough.

Good discussion, Louis. I would add that there is another term, kong1 'empty, hollow' which is frequently found living along with xu/shi. Typically traditional Yang style players say 'empty (xu) but not kong1'. This kong1 has a bad connotation of hollow, weak, incapable, fake, etc.

Do you know what the Chinese words are that denote empty and full in the I Ching? I'm thinking that even if they literally say "light and dark" or "moving and still" they are still an early citation of the same theories.

Louis, I agree with Polaris, very informative and much to think about. I thank you for your efforts on our behalf.In your opinion does the concept of xu/shi (empty/full) as you have presented it here preclude a 100/0 (or as near as humanly possible, to be more accurate) seperation of Yin/Yang energy between your legs as I have described in other posts? In other words, do you believe that the usage of seperating empty and full to a 100/0 seperation (or as near as can be) to be an incorrect interpretation of this theory on the part of those who practice it that way? Same question twice, I guess, but I wanted the question to be clear.

Yes, the ‘empty-empty full-full’ formula is a very tricky turn of phrase. I don’t think that it’s advocating, for example, to physically attack force with force; that would be antithetical to taiji principles. Rather, it should to be understood on a psychological level. It has to do with knowing your opponent so well that you can match his strategy, anticipate his response, and turn the tables on him. Another possible meaning of xuxu shishi is that it entails an understanding that the polarity of empty and full can reverse in the blink of an eye. Things are not always what they seem, and if you have rigid expectations about how your tactics will work, you may find yourself in trouble.

I can relate this to experiences I’ve had in push hands. Perhaps you and others have had similar experiences where you’re pushing hands with a particularly adept practitioner, and after a bit of time you have a sort of involuntary feeling that “I’ve got him!”—It’s a feeling that you’ve got a perfect purchase, you’ve hit pay dirt, you’ve got the keys to the Buick. So with absolute confidence you follow through with what you think will be a decisive nudge, only to find yourself spinning and careening clumsily off into space. This sort of situation certainly has a good deal to do with physical skill, but it has a more important psychological component. Somehow your opponent has tricked you into thinking he or she was vulnerable, only to ambush you at your moment of confidence.

Again, my reasoning for this interpretation of the xuxu shishi line in the Yang Banhou formula is based on my discovery of the same phrase in the Romance of the Three Kingdoms novel (a very popular novel, the stories of which were accessible to people of all walks of life through story tellers, plays, etc.), and the fact that it appears there in a specific context having to do with psychological warfare and deceptive strategy. The psychological meaning is also supported, I think, by the use of the word “shen” in the line: “Using empty-empty full-full, the spirit gathers within.” The word “shen” in this kind of context usually connotes a pervasive awareness, inclusive of conscious and unconscious processes. It’s the same sort of usage of “shen” found in the Sunzi line I quoted: “One who is able to change and transform in accord with the enemy and wrest victory is termed spiritual!”

This, of course, is my interpretation, and my research summarized in the above post informs the way I translated the Yang Banhou koujue. Other translations I’m aware of are Douglas Wile’s and Yang Jwing-ming’s, so you can read those for comparison. I’m open to criticism, to be sure.

I wouldn’t want to go so far as to say that interpretation is wrong, because I think that interpretation is in large part a rhetorical presentation with a specific training rationale. You already know my view that 100/0 weighting is not a viable proposition as long as part of the empty foot is touching the ground. I also think that the supportive role of the empty foot in the body’s equilibrium is involuntary. That’s how the human body equilibrates, it “accounts” for the fact that a foot is in contact with the earth or not, and seeks equilibrium accordingly. In other words, Yang Zhenji’s comments about empty stances were not prescriptive, but descriptive. And yes, I would disagree with an interpretation that held one leg to be exclusively yin and one exclusively yang. Classically that’s not what yinyang polarity is about, and the taiji classics make that clear.

I’m not sure what words you’re referring to in the Yijing for empty and full; light and dark; or moving and still. To my knowledge, although the words “xu” and “shi” appear in the core text (the Zhouyi), they do not appear together as they do in the Sunzi and other texts. The later book that we know as the Yijing includes a good deal of commentary or “wings” that come from the late warring states period and the early Han. That’s where most of the correlative language actually came from. The original oracle text didn’t really include any discussion of yinyang or five phases; that came later. However, xu/shi is but one of a vast set of correlative pairings found in early Chinese thinking, so it can be seen as having plenty of company, and they all are viewed as falling under the “greater principle” of yinyang polarity, as in the line in the taiji terms dictionary I quoted above: ‘Yet the many faceted transformations of empty and full converge under the greater principle of empty/full, what is called “always this one empty/full.”’ This is clearly a reference to the philosophical concept of taiji, from which taijiquan takes its name.

Thank you. I did some looking, and the most prevalent examples of complementary opposites that I found in the earliest strata of the Chou I were terms like:

Ming2 and Hui4 for light and dark,

Tian1 and Di4 for heaven and earth,

and of course, Qian2 and Kun1 for the first two hexagrams. There are also terms describing the lines in the later strata such as moving and still, opening and closing and the like.

I believe, if I've gotten this part of my instruction right (my T'ai Chi lineage descends from Yang Pan-hou), that at least part of what Yang Pan-hou was on about with the full/full, empty/empty, etc. characterizations was describing an attitude of commitment to the principle of distinguishing full and empty. An example my teachers use in this regard is to observe how someone sits in a chair. Most people, even though their posteriors are indeed on the seat, will still support their bodies somehat upright with muscular tension in their trunk, they don't sink or "root" enough to actually sit. If a person has relaxed to the point that the latent tension in the body doesn't dominate their framework 24/7, then when they sit in the chair, they are actually sitting, relaxed and at ease, using just enough muscle power to keep from melting onto the floor! The Ch'an Buddhists explore this theme in at least some of their meditations. So to be full/full in that sense is to be 100% full in Spirit, Intent and Breath (shen, yi, qi) when you "suddenly appear" and to be empty/empty is to be as empty as you possibly can be in the same senses when it is time to "suddenly disappear." The full/empty, empty/full are also stages in the process, representing more transitional stages of an encounter. A corollary that we have is in our meditative techniques - we speak of four classifications of states of meditation in Wu style:1. Stillness inside, stillness outside.2. Stillness inside, movement outside.3. Movement inside, stillness outside.4. Movement inside, movement outside.

You may be aware of this site, but I've found it to be a good source for literal translation and even a bit of a concordance for the actual characters used in the Chou I:

Louis, I still feel that "you gotta keep 'em seperated", but I'm also finding good merit in NOT keeping them seperated so completely all the time. My feelings are most likely influenced by long training in a philosophy of pure 100/0 physical seperationg except in certain postures for very specific reasons.But now I'm beginning to realise that absolutes like that can lead to stagnation and it is time to start to accept other ways of thinking and moving.I'm not 100 percent convinced, however, that going to a 70/30 or even a 90/10 split is the answer. Not yet.

I must bow to reality in that when one foot touches the ground my body becomes aligned in a different way and try as I might at least 2% of my "weight" is present in that foot. However I also believe this is covered by the theory I learned at WTCCA of keeping "intent" in that foot. Polaris would certainly be able to verbalise the idea in a better way than I can, but I'll give it a shot.

If my body is aligned to accept one foot being on the ground rather than up in the air (as in stepping) then that means I would have the physical "intent", or perhaps "ability" may be a better word to use as it leads to less confusion, to use it.My mind intent is to not use that leg for support of my bodies frame at all, but the physical reality is that it is there and must be ready to be utilized.By not intending to use the leg, no mind intent, I am (IMHO) adhering to the idea of keeping full and empty seperated as a mental state (I must be mental for even trying to get this right), but reality dictates that there be some minute measure of support of and for that leg by my body in order for it be able to be utilized instantly in any way necessary. This is where physical "intent" or "ability" comes into play.As I have previously mentioned, being able to move in any direction with my empty leg, step, kick, open my hip, set it down fully and lean my weight into it, whatever, at any time and without having to re-arrange the rest of my body first is an ability I covet highly. It has saved my rear end a couple of times, I'm not ready to give it up yet.If I am maintaining only a minute quantity of support for my body in that leg, then only a minute amount of re-arrangement of my body needs to be made to do just that. With a bare minimum of shifting and time I can be in position to do anything with that leg I so desire. I see this as a great way to maintain being nimble and agile.However, if I am maintaining a significant portion of support for my body through that leg, then a significant amount of re-arrangement of my body needs to be made to get that leg ready to go where I need it and time is lost in this transitional phase. Time I may not have. It seems to me only logical that if I maintain my body in such a way that only a small amount of movement is necessary to go in any direction then less time is required to do so, if a large amount of movement is required than more time is necessary to achieve the same end.Also, the Wu style I trained in uses primarily movement from the hip. I can now see that there is movement from the waist as well, but the primary focus of how I was trained was movement from the hip. In this form of movement, you can generate much more, or accept and redirect much more, power if you keep your body weight seperated to only one leg at a time.

Now...That being said, I have been having an insight into movement generated from the "waist". (Side note, am I correct in that the chinese term for this region is "kao"?). Utilizing this form of movement, I can see clear advantages for keeping a more widely spaced lower frame. This will allow a freer turn of the waist than if you had all your weight on only one pivot point.

So at this point in time, I'm having a struggle.I don't think it's insurmountable, I just feel that I have a lot more learning to do before condem or condone one way or the other.There has to a happy medium. A point where both of these styles of movement can meet and be integrated together.Some day, I hope to find it.

Louis, Awesome!Great discussion going on here! There is too much for me to absorb all at once, so I will ask one question at a time, but be sure there are more on their way.

You quoted..."Each part has its point of empty/full. Everywhere there is always this one empty/full."

I am wondering if this is a case of 'superimposed', or if it is closer to the comparison of two cogs or wheels? As in a large wheel and a small wheel. If so, do you think these 'wheels' affect each other directly or would they be driven from independant sources? In other words, is the 'little' wheel limited to the control of the big wheel? Is the big wheel limited to the contol of the little wheel? Dependant or independant? Do these wheels turn like a large and small cog, at different speeds? The small turning faster to accomodate the large revolutions of the big wheel? Completely random, or is there a pattern which can be followed (as in 'life cycles' or chakra cycles)throughout the rotations?Patterns lead to predictability, I am seeking patterns.

Louis, I've never had any trouble with full/empty substantial/unsubstantial. As for the military idea of hitting them where they ain't: why knock the wall down to gain entry when there's an open gate?

I've hundreds of ideas in the area, so I can't even brush the surface. Generally, the pairing of related opposites leads people to look at a larger picture than otherwise.

Wushuer, that mobility is exactly the point. Every position has benefits and drawbacks. Limitations are the name of the game, it's a matter of learning how to use those limitations as levers. With both feet on the ground you can still move; it's a matter of technique and clarity.

Polaris, You need to seek the unpredictable as well as well as the predictable. Forget randomness and try for the spontaneous. That which is spontaneous is also unpredictable. As Steve James once said there is technique everywhere, there is no technique.

You learn the patterns so that your body is healthy and able to move any which way and still be in good alignment. Physical combat is a living thing, unconstrained by rules. How predictable do you wish to be in a fight?

DavidJ, "There is technique everywhere, there is no technique"- Steve James.

I think I've heard that expressed as "The way of no way, the way of all ways"-???Do these both contain the same connotations?

I know I can study patterns,and maybe avoid repetitious errors in future by doing so,(learn from past errors) or perhaps determine an opponents moves in advance by studying his repetitive gestures. As for 'unpredictability' or' 'spontaneity,I am really not sure how I could study someone elses 'unpredictability' and learn something, but I could try to develop my spontaneous nature as you said, to not be predictable to the opponent. Thanks for pointing that fact out, I can see the merit of developping a spontaneous nature, or being unpredictable, I am just not sure how I could actually study it.